sacrum vs. coccyx

sacrum vs. coccyx: What's the difference?

The sacrum is a large flat bone in the lower part of the spine, forming the rear section of the pelvis in humans. The coccyx, also known as the tailbone, is the very end of the spine, located right below the sacrum. Both are triangular and are composed of multiple vertebrae fused into a single bone.

sacrum

[sak-ruhm, sey-kruhm] / ˈsæk rəm, ˈseɪ krəm /

noun

Anatomy.

plural

sacra

a bone resulting from the fusion of two or more vertebrae between the lumbar and the coccygeal regions, in humans being composed usually of five fused vertebrae and forming the posterior wall of the pelvis.

coccyx

[kok-siks] / ˈkɒk sɪks /

noun

plural

coccyges

a small triangular bone forming the lower extremity of the spinal column in humans, consisting of four ankylosed rudimentary vertebrae.
a corresponding part in certain animals.